The present invention is directed to an apparatus for measuring and monitoring a force adjustment and an ultrasound adjustment in suitable time intervals for bonding machines, particularly bonders, which operate with ultrasound and preferably serve the purpose of bonding terminal wires which lead from semiconductor bodies to interconnects of non-conductive substrates.
Basically, bonding is a mechanical connecting process which also simultaneously produces an electrical contact of the parts to be joined. This is achieved in wire bonding in that two parts (for example a chip and a wire) which are initially not mechanically identical are connected to one another by modifying their surface structure. The modification is thereby produced on at least one part.
In the simplest case, this modification of the surface structure can ensue as a result of by the mere application of force. The force as well as temperature can then be reduced with additional use of ultrasound energy.
Extremely high demands are made of the quality of the connection in micro-electronics. The contacting of integrated circuits (IC) occurs with thin (about 17 through 50 .mu.m) gold or aluminum wires. These wires are automatically applied to the IC and to the carrying frame by bonders.
The precision of the machines (contacting machines or bonders) must increase for smaller wires and integrated circuits. These machines automatically identify the pads on a chip and subsequently produce the wire bonds. In order to guarantee that the contacting machines maintain this precision during daily operation, it is necessary to be able to monitor certain elementary functions.
An optimized range of the bonding parameters (bonding force, ultrasound amplitude, bonding time and bonding temperature) which can guarantee the quality required for the component part is usually determined for each structural shape or form and contacting machine. This set of parameters, naturally, varies from structural form to structural form and likewise has variations with respect to the contact machines
This optimized work range can be adhered to only with regular monitoring and potential follow-up adjustment of these contacting machines.
The object of the present invention is to design the apparatus initially defined to be able to measure the static and dynamic forces occurring when bonding, the ultrasound amplitude, and the bonding time during a single simulated bonding process in a force measurement of the bonders. Great value is thereby to be placed on a flexible format so that the force pick-up can be easily attached to different bonders.
In particular, individual phases or details such as, for example, transients or chronological sequences, should be investigated. Over and above this, individual bonders should be set to the parameters specified for them in the operating conditions and should be subsequently operated with these parameters.
German published application No. 32 33 629 shows and describes a method and an apparatus for producing connections with ultrasound. This involves a stationary apparatus with which the force is identified and monitored, that is the force which is required for parting the connecting tool from one of the component parts participating in the connection after the end of the connecting process. This, however, assumes an operation on the machine and an alteration of the machine which is either impossible in many machines or can be implemented only with relatively great outlay.
The apparatus disclosed by U.S. Pat. No. 3,857,279 likewise involves a measuring system stationarily integrated into the machine which measures and interprets harmonics of the ultrasound. A force measurement does not occur.